C_5烯烃与甲醇醚化反应动力学的研究进展

RECENT RESEARCHES ON KINETICS OF TERTIARY AMYLMETHYL ETHER SYNTHESIS WITH C_5-OLEFINS AND METHANOL IN THE LIQUID PHASE

讨论了C5烯烃液相合成甲基叔戊基醚的反应机理,分析了各种的动力学模型。认为表面反应是反应控制步骤,甲醇强吸附在催化剂的表面,在推导动力学方程时必须用活度代替浓度,为了保证方程的精确度,活度系数的准确计算非常重要。活度系数的计算可采用UNIQUAC、UNIFAC、WILSON等方法,哪种方法更适合醚化反应物系没有定论,但要注意的是所采用的方法必须与推导热力学平衡常数时保持一致。考虑到工业上主要应用管式反应器,甲醇的活度随其浓度的下降而增大,在反应器的轴向变化很大,反应速率方程中的活度应与热力学平衡常数关联在一起计算。主要的分歧在于甲醇浓度对反应速率的影响,各文献报道有差异。另外在推导动力学方程时将两种烯烃集总在一起作为一个组分处理,未见实验研究支持该假设。在反应体系中是醚化反应速率快还是烯的异构化反应快,反应是按单活性位还是双活性位机理进行存在争论。

The reaction mechanism of Tertiary amyl methyl ether （TAME） synthesis with C5-olefines was discussed. Various kinetic models were analyzed in detail and the limitation of these models was summarized. In the reaction system, surface reactions are the control steps. The reaction system is highly non-ideal because of the high polarity of methanol. Methanol is highly adsorbed on the surface of catalyst. In deriving kinetic equations, the concentrations of the reactants should be replaced by the activities. The equations which can be adopted for calculating activities are UNIQUAC, UNIFAC or WILSON. It must be emphasized that, no matter which method is adopted, it should coincide with the method for deriving the equilibrium constants. Considering the activity of methanol changing sharply along the reactor lateral, the activities should be calculated with the equilibrium constants. There are some disputes in the researches such as the influence of methanol on the reaction rates; the rationality of taking the two isoamylenes as one reactant; which reaction rate is faster between the etherification and isomerization; which reaction mechanism is the best one.